Dealer diagnosis found that my driver side catalytic converter is bad but are recommending i replace both converters and all the air sensors. What is wrong with replacing just the bad converter? Is there any real disadvantage in using an aftermarket replacement. The differences in prices are very significant. Please direct me if there threads existing on these issues.

 

If one went it's only a matter of limited time until the other goes. And yes, oxygen sensors are usually replaced with the catalytic converters.

 

I would replace both. No real disadvantages to utilizing aftermarket. Personally, I would get them welded into the rest of the exhaust system and +1 on replacing all O2 sensors for peace of mind..

 

There are two banks, controlled for AFR separately, so I see no reason to assume the other cat is also bad or nearly dead. It may be but that's an expensive assumption.

You could test it or wait and see.

 

I've replaced one of my cats before with an aftermarket from Eastern Catalytic. Relatively inexpensive, and I was pleased with it. Not a real difficult installation either.

 

Thanks for the responses

 

im sorry i feel your pain i have a bad cat so bought an after market one for both sides and i still had the code and dealer told me $4500 to replace both. I paid $5400 for the car no way im spending $4500 on cats and i kinda got lucky bc washington state just removed the emissions law so i just ignore the cel light. I do check it often just to make sure no codes pop up but i still have the p0420 and p0430 thats boths cats. BTW i have a 2007 VDP

 

Often the first hint of a failing cat is a very stinky exhaust. I'm more inclined to suspect the O2 sensors if the exhaust doesn't stink.